Astronomers map vast in our cosmic neighborhood 22 July 2019

responsible for that motion, and construct three- dimensional maps of our local .

Galaxies not only move with the overall expansion of the universe, they also respond to the gravitational tug of their neighbors and regions with a lot of mass. As a consequence, they are moving towards the densest areas and away from regions with little mass—the voids.

Although we live in a cosmic metropolis, back in 1987 Tully and Richard Fisher noted that our is also at the edge of an extensive empty region that they called the Local Void. The existence of the Local Void has been widely accepted, but it remained poorly studied because it lies behind the center of our galaxy and is therefore heavily obscured from our view.

Now, Tully and his team have measured the motions of 18,000 in the Cosmicflows-3 A smoothed rendition of the structure surrounding the compendium of galaxy distances, constructing a Local Void. Our Milky Way galaxy lies at the origin of the cosmographic map that highlights the boundary red-green-blue orientation arrows (each 200 million between the collection of and the absence of lightyears in length). We are at a boundary between a matter that defines the edge of the Local Void. large, low density void, and the high density Virgo They used the same technique in 2014 to identify cluster. Credit: R. Brent Tully the full extent of our home supercluster of over one hundred thousand galaxies, giving it the name Laniakea, meaning "immense heaven" in Hawaiian. An astronomer from the University of Hawai?i For 30 years, astronomers have been trying to Institute for Astronomy (IfA) and an international identify why the motions of the Milky Way, our team published a new study that reveals more of nearest large galaxy neighbor Andromeda, and the vast cosmic structure surrounding our Milky their smaller neighbors deviate from the overall Way galaxy. expansion of the Universe by over 600 km/s (1.3 million mph). The new study shows that roughly The universe is a tapestry of galaxy congregations half of this motion is generated "locally" from the and vast voids. In a new study being reported in combination of a pull from the massive nearby The Astrophysical Journal, Brent Tully's team Virgo Cluster and our participation in the expansion applies the same tools from an earlier study to map of the Local Void as it becomes ever emptier. the size and shape of an extensive empty region they called the Local Void that borders the Milky Representations of the void can be seen in a video Way galaxy. Using the observations of galaxy (below) and, alternatively, with an interactive model motions, they infer the distribution of mass (below). With the interactive model, a viewer can

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pan, zoom, rotate, and pause/activate the time evolution of movement along orbits. The orbits are shown in a reference frame that removes the overall expansion of the universe. What we are seeing are the deviations from cosmic expansion caused by the interactions of local sources of .

More information: Cosmicflows-3: Cosmography of the Local Void, The Astrophysical Journal (2019). DOI: 10.3847/1538-4357/ab2597

Provided by University of Hawaii at Manoa APA citation: Astronomers map vast void in our cosmic neighborhood (2019, July 22) retrieved 1 October 2021 from https://phys.org/news/2019-07-astronomers-vast-void-cosmic-neighborhood.html

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